What we can learn from twins…on addiction

The last few years of my academic career, my research focus has been on the genetic and environmental influences of alcohol use. Addiction research is a microcosm of life. You can study risk and resilience in so many different ways through the lens of addiction. Why do some people drink? Why do some abstain from drinking? What keeps some people drinking? What makes some people stop? If you take out the word “drink” from those questions and insert whatever word is applicable in your life, you will also see that it’s not about drinking – it’s about finding a balance. What is something you’ve struggled with that you’ve tried to stop? Have you seen other people stop or start something and wondered what it is that they’re doing and you’re not? Well, it’s these types of questions that intrigue me.

One way addiction research is studied is by looking at twins. There’s several twin registries out there and studies done on twins to determine genetic and environmental influences on a variety of behaviors. You can understand how much of a certain characteristic is associated with your genes, shared environment, or individual environment. You can do this because when you study twins there are two types: identical (or monozygotic) and fraternal (or dizygotic) twins. Identical twins share 100% of their genes. Fraternal twins are basically just like any other sibling, sharing only 50% of their genes. Except there are a couple big things that separate fraternal twins from other siblings: (1) they shared a womb together and (2) they were raised relatively similarly since they were raised at the same time as opposed to generational differences. Also, both Identical and fraternal twins share 100% of their shared environment because they grew up together and more or less were surrounded by the same upbringings, hardships, or circumstances.

Although you can use twins to study pretty much anything, I use it to understand addiction and alcoholism better. Through many studies, it’s been found that shared environmental factors play a large role in whether someone initiates use. This means that a significant reason why people START to drink is because of shared environmental aspects. This could be family environment, shared peer networks, etc. BUT as someone starts to drink more and he/she develops an alcohol use disorder, an individual’s genes plays a bigger factor. That means that even though shared environment accounts for most of the reason why people start to drink, an indivdiual’s genetic expression accounts for most of the association with problem drinking.

What I hope you take away from this new research is that nothing is black and white. It’s not that only your genetics will determine your outcome or only your environment will, but there are influences from both and some more than others at different times. At the end of the day, regardless of your genes, environment, family, upbringing, it is your choice. Your life. Your way. What do you want for yourself? What choice can you make aligned with that? Even if you have some risk factors associated with higher rates of alcohol problems (or whatever it is that is going on in your life) that doesn’t mean it’s destined to happen. It just means that maybe you can take extra precautions to not go down a path you know you’d be better off avoiding. It’s just as if you have a predisposition to diabetes and perhaps you have a certain gene that makes it more likely that you’ll develop diabetes. However, there are certain medications, a type of diet, etc. that can help prevent such an event from occurring. It’s the same thing with addiction. Even if you have risk factors associated with the disease of addiction, it doesn’t mean that it will happen. And if it has happened, it doesn’t mean that you can’t make changes to keep it from coming back or stopping all together.

This post was inspired by a research article by Pagan et al. (2006) called Genetic and Environmental Influences on Stages of Alcohol Use Across Adolescence and into Young Adulthood. Search for it here on Google Scholar. Also, click here for a book written by Dr. Carol A. Prescott for more info on twin research.